Usage

Documentation

MPI is a popular library for distributed-memory parallel programming. It offers both point-to-point message passing and group communication operations (broadcast, scatter/gather, etc).

Open MPI is an implementation of the MPI standard that combines technologies and resources from several other projects (FT-MPI, LA-MPI, LAM/MPI, and PACX-MPI) in order to build the best MPI library available.

The Chicken MPI egg provides a Scheme interface to a large subset of the MPI 1.2 procedures for communication. It is based on the Ocaml MPI library by Xavier Leroy. The mpi library has been tested with Open MPI versions 1.2.4 - 1.4.5.

Initialization and time procedures

[procedure]MPI:init :: [ARG1 ...] -> UNDEFINED

Initializes the MPI execution environment. This routine must be called before any other MPI routine. MPI can be initialized at most once.

Spawns MAXPROCS identical copies of the MPI program specified by COMMAND and returns an intercommunicator and a vector of status values. ARGUMENTS is a list of command-line arguments. LOCATIONS is a list of string pairs (HOST * WDIR) that tell MPI the host and working directory where to start processes.

[procedure]MPI:finalize

Terminates the MPI execution environment.

[procedure]MPI:wtime :: VOID -> SECONDS

Returns the number of seconds representing elapsed wall-clock time on the calling process.

Handling of communicators

[procedure]MPI:comm? :: OBJ -> BOOL

Returns true if OBJ is an MPI communicator object, false otherwise.

[procedure]MPI:get-comm-world:: VOID -> COMM

Returns the default communicator created by MPI_Init; the group associated with this communicator contains all processes.

[procedure]MPI:comm-size :: COMM -> INTEGER

Returns the size of the group associated with communicator COMM.

[procedure]MPI:comm-rank :: COMM -> INTEGER

Returns the rank of the calling process in communicator COMM.

[procedure]MPI:comm-equal? :: COMM1 * COMM2 -> BOOL

Returns true if the two given communicators are for identical groups, false otherwise.

[procedure]MPI:comm-split :: COMM * COLOR * KEY -> COMM

Creates new communicators based on colors and keys.

[procedure]MPI:comm-create :: COMM * GROUP -> COMM

Creates a new communicator with communication group that spans all processes in GROUP and a new context. See the procedures in subsection Handling of communication groups for information on how to create process group objects.

[procedure]MPI:make-cart :: COMM * DIMS * PERIODS * REORDER -> COMM

Creates a new communicator with Cartesian topology information. Argument DIMS is an SRFI-4 s32vector that contains the number of dimensions of the Cartesian grid. Argument PERIODS is an SRFI-4 s32vector of the same length as DIMS that indicates if the grid is periodic (1) or not (0) in each dimension. Argument REORDER is a boolean value that indicates whether process ranking may be reordered.

[procedure]MPI:make-dims :: NNODES * NDIMS -> DIMS

Creates a division of processes in a Cartesian grid. Argument NNODES is the number of nodes in the grid. Argument NDIMS is the number of Cartesian dimensions. The return values is an SRFI-4 s32vector.

[procedure]MPI:cart-coords :: COMM * RANK -> COORDS

Determines process coordinates in Cartesian topology, given a rank in the group. The return value is an SRFI-4 s32vector of length NDIMS (the number of dimensions in the Cartesian topology).

Check for an incoming message. This is a blocking call that returns only after a matching message is found. Argument SOURCE can be MPI:any-source. Argument TAG can be MPI:any-tag.

Group communication

[procedure]MPI:barrier :: COMM -> UNDEFINED

Barrier synchronization.

[procedure]MPI:broadcast-TYPE :: DATA * ROOT * COMM -> UNDEFINED

Broadcasts a message from the process with rank root to all other processes of the group. TYPE is one of the following: fixnum, int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:scatter-TYPE :: DATA * SENDCOUNT * ROOT * COMM -> DATA

Sends data from the root process to all processes in a group, and returns the data received by the calling process. Argument SENDCOUNT is the number of elements sent to each process. Argument DATA is only required at the root process. All other processes can invoke this procedure with (void) as DATA. TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

Sends variable-length data from the root process to all processes in a group, and returns the data received by the calling process. Argument SENDCOUNT is the number of elements sent to each process. Argument DATA is only required at the root process, and is a list of values of type TYPE, where each element of the list is sent to the process of corresponding rank. All other processes can invoke this procedure with (void) as DATA. TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:gather-TYPE :: DATA * SENDCOUNT * ROOT * COMM -> DATA

Gathers data from a group of processes, where each process send data of the same length. Argument SENDCOUNT is the number of data elements being sent by each process. TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:gatherv-TYPE :: DATA * ROOT * COMM -> DATA

Gathers data from a group of processes, where each process can send data of variable length. TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:allgather-TYPE :: DATA * ROOT * COMM -> DATA

Gathers data of variable length from all processes and distributes it to all processes. TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:reduce-TYPE :: DATA * OP * ROOT * COMM -> DATA

Reduces values on all processes within a group, using a global reduce operation, and return the result at the root process. OP is one of the following: MPI:i_max, MPI:i_min, MPI:i_sum, MPI:i_prod, MPI:i_land, MPI:i_lor, MPI:i_xor (integer operations); and MPI:f_max, MPI:f_min, MPI:f_sum, MPI:f_prod (floating point operations). TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:allreduce-TYPE :: DATA * OP * COMM -> DATA

Reduces values on all processes within a group, using a global reduce operation, and return the result at each process. OP is one of the following: MPI:i_max, MPI:i_min, MPI:i_sum, MPI:i_prod, MPI:i_land, MPI:i_lor, MPI:i_xor (integer operations); and MPI:f_max, MPI:f_min, MPI:f_sum, MPI:f_prod (floating point operations). TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

[procedure]MPI:scan-TYPE :: DATA * OP * COMM -> DATA

Computes a partial reduction across the processes in a group. OP is one of the following: MPI:i_max, MPI:i_min, MPI:i_sum, MPI:i_prod, MPI:i_land, MPI:i_lor, MPI:i_xor (integer operations); and MPI:f_max, MPI:f_min, MPI:f_sum, MPI:f_prod (floating point operations). TYPE is one of the following: int, flonum, bytevector, s8vector, u8vector, s16vector, u16vector, s32vector, u32vector, f32vector, f64vector

Round-robin routines

The following variants of fold, map and for-each process lists in round-robin fashion on MPI nodes: for a given node n, only list elements whose index is a modulo of n will be processed on this node.

License

Copyright 2007-2013 Ivan Raikov and the Okinawa Institute of Science and Technology
Based on the Ocaml MPI library by Xavier Leroy.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
A full copy of the GPL license can be found at
<http://www.gnu.org/licenses/>.